#!/usr/bin/env python
# -*- coding: utf-8 -*-#

#-------------------------------------------------------------------------------
# Name:         find_num.py
# Description:  
# Author:       handa
# Date:         2022/5/20
#-------------------------------------------------------------------------------

l = [1,3,5,7,9,11]
def find_num(l,x):
    if not l:
        return
    if l[0] == x:
        return l[0]
    else:
        return l[0] + find_num(l[1:],x)

r = find_num(l,15)
print(r)